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$FreeBSD: releng/10.2/lib/libc/sys/cpuset.2 249716 2013-04-21 06:46:41Z joel $
.Dd January 8, 2010 .Dt CPUSET 2 .Os .Sh NAME .Nm cpuset , .Nm cpuset_getid , .Nm cpuset_setid .Nd manage CPU affinity sets .Sh LIBRARY .Lb libc .Sh SYNOPSIS n sys/param.h n sys/cpuset.h .Ft int .Fn cpuset "cpusetid_t *setid" .Ft int .Fn cpuset_setid "cpuwhich_t which" "id_t id" "cpusetid_t setid" .Ft int .Fn cpuset_getid "cpulevel_t level" "cpuwhich_t which" "id_t id" "cpusetid_t *setid" .Sh DESCRIPTION The .Nm family of system calls allow applications to control sets of processors and assign processes and threads to these sets. Processor sets contain lists of CPUs that members may run on and exist only as long as some process is a member of the set. All processes in the system have an assigned set. The default set for all processes in the system is the set numbered 1. Threads belong to the same set as the process which contains them, however, they may further restrict their set with the anonymous per-thread mask.
p Sets are referenced by a number of type .Ft cpuset_id_t . Each thread has a root set, an assigned set, and an anonymous mask. Only the root and assigned sets are numbered. The root set is the set of all CPUs available in the system or in the system partition the thread is running in. The assigned set is a subset of the root set and is administratively assignable on a per-process basis. Many processes and threads may be members of a numbered set.
p The anonymous set is a further thread-specific refinement on the assigned set. It is intended that administrators will manipulate numbered sets using .Xr cpuset 1 while application developers will manipulate anonymous sets using .Xr cpuset_setaffinity 2 .
p To select the correct set a value of type .Ft cpulevel_t is used. The following values for .Fa level are supported: l -column CPU_LEVEL_CPUSET -offset indent t Dv CPU_LEVEL_ROOT Ta "Root set" t Dv CPU_LEVEL_CPUSET Ta "Assigned set" t Dv CPU_LEVEL_WHICH Ta "Set specified by which argument" .El
p The .Fa which argument determines how the value of .Fa id is interpreted and is of type .Ft cpuwhich_t . The .Fa which argument may have the following values: l -column CPU_WHICH_CPUSET -offset indent t Dv CPU_WHICH_TID Ta "id is lwpid_t (thread id)" t Dv CPU_WHICH_PID Ta "id is pid_t (process id)" t Dv CPU_WHICH_CPUSET Ta "id is a cpusetid_t (cpuset id)" t Dv CPU_WHICH_IRQ Ta "id is an irq number" .El
p An .Fa id of '-1' may be used with a .Fa which of .Dv CPU_WHICH_TID , .Dv CPU_WHICH_PID , or .Dv CPU_WHICH_CPUSET to mean the current thread, process, or current thread's cpuset. All cpuset syscalls allow this usage.
p A .Fa level argument of .Dv CPU_LEVEL_WHICH combined with a .Fa which argument other than .Dv CPU_WHICH_CPUSET refers to the anonymous mask of the object. This mask does not have an id and may only be manipulated with .Xr cpuset_setaffinity 2 .
p .Fn cpuset creates a new set containing the same CPUs as the root set of the current process and stores its id in the space provided by .Fa setid . On successful completion the calling process joins the set and is the only member. Children inherit this set after a call to .Xr fork 2 .
p .Fn cpuset_setid attempts to set the id of the object specified by the .Fa which argument. Currently .Dv CPU_WHICH_PID is the only acceptable value for which as threads do not have an id distinct from their process and the API does not permit changing the id of an existing set. Upon successful completion all of the threads in the target process will be running on CPUs permitted by the set.
p .Fn cpuset_getid retrieves a set id from the object indicated by .Fa which and stores it in the space pointed to by .Fa setid . The retrieved id may be that of either the root or assigned set depending on the value of .Fa level . .Fa level should be .Dv CPU_LEVEL_CPUSET or .Dv CPU_LEVEL_ROOT to get the set id from the process or thread specified by the .Fa id argument. Specifying .Dv CPU_LEVEL_WHICH with a process or thread is unsupported since this references the unnumbered anonymous mask.
p The actual contents of the sets may be retrieved or manipulated using .Xr cpuset_getaffinity 2 and .Xr cpuset_setaffinity 2 . See those manual pages for more detail. .Sh RETURN VALUES .Rv -std .Sh ERRORS The following error codes may be set in .Va errno : l -tag -width Er t Bq Er EINVAL The .Fa which or .Fa level argument was not a valid value. t Bq Er EDEADLK The .Fn cpuset_setid call would leave a thread without a valid CPU to run on because the set does not overlap with the thread's anonymous mask. t Bq Er EFAULT The setid pointer passed to .Fn cpuset_getid or .Fn cpuset was invalid. t Bq Er ESRCH The object specified by the .Fa id and .Fa which arguments could not be found. t Bq Er EPERM The calling process did not have the credentials required to complete the operation. t Bq Er ENFILE There was no free .Ft cpusetid_t for allocation. .El .Sh SEE ALSO .Xr cpuset 1 , .Xr cpuset_getaffinity 2 , .Xr cpuset_setaffinity 2 , .Xr pthread_affinity_np 3 , .Xr pthread_attr_affinity_np 3 .Sh HISTORY The .Nm family of system calls first appeared in .Fx 7.1 . .Sh AUTHOR .An Jeffrey Roberson Aq jeff@FreeBSD.org